The present invention relates to silicon-containing polymers, especially grafted polysilanes useful as photoinitiators having enhanced photoinitiation properties for vinyl type resins and a process for preparing them.
A lot of organic compounds which generate radicals upon exposure to, for example, ultraviolet light are known as photoinitiators for vinyl type resins. Among them are included polymeric ones, including not only those having advantages such as being superior in the compatibility with vinyl type resins with which they are to be combined, but also those generating only small amounts of radicals and those poor in the compatibility with resins to be crosslinked using them. Thus, a new type of photoinitiators are desired inevitably.
Further, polyorganosiloxanes and acrylic resins are in wide use as adhesives and potting agents for electronic devices and components. Many of them are of the type which undergoes crosslinking upon exposure to light, and photoinitiators suitable for them are keenly desired.
It is an object of the present invention to provide novel silicon-containing polymers useful as a new type of photoinitiators, as well as precursors thereof and a process for preparing them.
The present inventors succeeded in the preparation of grafted polysilanes which possess enhanced photoinitiation properties for vinyl type resins.
The novel grafted polysilanes which include both grafted cyclic polysilanes and grafted networked polysilanes may have various grafted chains on the silane backbone. The chains to be grafted on the silane backbone can be selected widely from those having various compositions and molecular lengths so as to have a good compatibility with a particular vinyl type resin.
The grafted polysilane of the present invention is produced by firstly producing a polysilane by utilizing either a Wultz reaction or a metallocene reaction, and then grafting a grafting compound onto the polysilane by utilizing either a hydrosilation reaction, a condensation reaction or a catalysis reaction.
In the present invention, the term xe2x80x9cpolymerxe2x80x9d is used in the sense of including both oligomer and polymer.